Central to the success of many recent health system reforms is the implementation of new primary health care delivery models. The central characteristic common to these new models usually emphasises interdisciplinary collaboration. Using empirical research, this paper studies interdisciplinary collaboration among various groups of professionals within an original Canadian primary health care delivery model, the Quebec Community Health Care Centres (CCHCs). The entire population of more than 150 CHCCs have been surveyed. The goals of this study are (1) to measure the achieved intensity of inter-professional collaboration among Quebec CHCCs, and (2) to identify the organisational and professional factors fostering or limiting interdisciplinary collaboration. The results show that Quebec CHCCs have reached modest results in achieving interdisciplinary collaboration especially since interdisciplinary collaboration is a central objective that has been pursued for more than 25 years. This study demonstrates that the main factors associated with interdisciplinary collaboration are closely linked to work group internal dynamics. Interdisciplinary collaboration is linked to the simultaneous and antagonistic effect of some central intragroup process factors. Conflicting values and beliefs are present that both enhance and limit interdisciplinary collaboration. The presence of conflicting stimuli seriously undermines the strength of the CHCC work group's shared beliefs and strongly limits interdisciplinary collaboration. The results also stress the importance of administrative formalisation initiatives to enhance collaboration among different professions. The efficacy of formalisation in this context is based on its capacity to offer an articulated and operative interdisciplinary framework that can generate a counteractive effect to the traditional professional framework. It offers concrete rules that help align the work group beliefs with interdisciplinary values. The formalisation of functions and processes appears thus to be an interesting means to further interdisciplinary collaboration.